In recent years, as a result of the remarkable increase in the amount of information to be handled by information apparatuses, such as a router, a server, and a storage, it is clearly recognized that the electric transmission in the interconnection between the information apparatuses, or between boards, or in a backplane is reaching its limit, and hence the need for interconnection by optical transmission is increased.
For this reason, an interface module for optical interconnection is also developed.
As a light source of the optical module for optical interconnection, a VCSEL (Vertical Cavity Surface Emitting Laser) is used in many cases. As reasons for this, there are listed such characteristics as low power consumption, low cost, high coupling efficiency with optical fibers, and high two-dimensional integration and paralleling properties. Since the VCSEL has such properties, it is most suitable as the light source used for the optical interconnection module in the apparatus.
The emission direction of the VCSEL is vertical to a substrate. In other words, the VCSEL emits a light beam in the direction vertical to the substrate.
An optical interface module of this type is configured by a substrate on which an optical element, such as the VCSEL, and a driver IC, are mounted, a via substrate which transmits a signal from on the substrate to a mounting board, and a case to which a light extraction section, such as a lens, is attached.
As an example of a related-art optical module, there is disclosed in Patent Document 1 “a photoelectric composite module and an optical input/output apparatus using the module as a component”.
FIG. 1 shows a sectional view of the optical module disclosed in Patent Document 1.
On a transparent plate 601 in which an interlayer wiring is formed, and on the upper and lower surfaces of which wiring patterns are formed, an optical element 602 for transmitting or receiving an optical signal is connected to wiring electrodes by flip chip mounting, and an input/output IC 603 for adjusting the current amplitude of the optical element (a driver IC in the case where the optical element is a light emitting element, or an electric amplifier IC in the case where the optical element is a light receiving element) is also similarly connected to wiring electrodes by flip chip mounting.
Further, on the transparent plate 601, the optical coupling between the optical element and an optical connector is realized via optical coupling means such as a lens. A signal line between the input/output IC and a board on which the optical module is mounted is connected to an electrode on the board from the transparent plate 601 via a via substrate (interlayer wiring board) 604. The heat generated by the driver IC is dissipated in the direction from under the optical module to the mounting board.
In the optical interface module of this type, it is necessary to restrict the optical transmission path within the height of a rack housing the board, and hence it is necessary to provide an optical-axis changing function in the optical connector which is optically coupled with the optical interface module.
As a related art of such optical connector, “an optical module” is disclosed in Patent Document 2.
FIG. 2 shows a configuration of the optical connector disclosed in Patent Document 2. The optical connector is configured such that V-grooves 701 for positioning fibers and a 45-degree inclined mirror 702 are provided in a connector portion, and that an optical fiber array 703 is mounted in the V-grooves 701 and is pressed by a cover glass 704. A light beam emitted from the optical fiber array 703 is once emitted in free space, and is then reflected by the 45-degree inclined mirror, so as to be emitted from the optical connector in the state where the optical path thereof is bent by 90 degrees. Then, the light beam is coupled with an optical interface module via optical coupling means such as a lens.
Patent Document 1: Japanese Patent Laid Open Publication No. 2004-31508
Patent Document 2: Japanese Patent Laid Open Publication No. 2003-207694
Patent Document 3: Japanese Patent Laid Open Publication No. 10-186183